Industry accepted computer processing standards use the concept of virtual slots, wherein multiple modules, cards or boards are interconnected. Virtual slot techniques permit the use of self stacking modules, cards or boards over a processor bus to allow multiple cards on a system without the burden of backplanes. The processor is logically connected to the stacked cards through the bus, and a connection to the bus is shared by the stacked cards.
Processor resources, such as chip select signals, interrupts, common clocks, etc., are allocated across the stacked cards. Manual settings may be used to associate the cards to the resources. This allows similar or even dissimilar hardware units to be cascaded or stacked with different jumper/switch settings or loaded with configured software, so that resources may be distributed without clash. Such jumper/switch settings, software or other manual settings may require system knowledge to set or configure properly. Lack of such knowledge, or mistakes in making the settings can lead to performance and resource clash issues. Some system flexibility, such as the order cards are stacked, may also be sacrificed with this conventional approach.